A sphygmomanometer is a clinical apparatus for measuring the blood pressure. Such devices generally comprise an inflatable cuff which is wrapped around a human limb usually the upper arm of a patient. The cuff is usually connected by a conduit, generally rubber tubing, to a resilient hand bulb, which acts as a hand pump, and is inflated by repetitively squeezing the bulb. The cuff is connected to a pressure-indicating manometer device or pressure gauge which has a pressure-calibrated dial and a pressure needle, which is movable over the latter. The pressure gauge needle is operatively connected by a conduit, also usually rubber tubing, to the cuff, and is movable in response to changes in air pressure in the cuff. A manually operable bleeder valve, or other pressure relief device, is provided to slowly bleed air from the inflated cuff. In use, sufficient pressurized air is pumped into the inflatable cuff until the inflated cuff tightens sufficiently to occlude the brachial artery in the upper arm, i.e., stop the blood flow therein. A stethoscope is applied over the artery below the cuff, and air is gradually allowed to escape through the bleeder valve from the cuff until a pulsing rush of blood can be heard. The pressure needle on the gauge at this point indicates the systolic pressure or the highest pressure in the arteries during contraction of the heart.
As deflation of the cuff continues, the air pressure within the cuff falls, and the needle successively indicates lower and lower pressure readings. The diastolic pressure, or lowest pressure in the artery during diastole, or relaxation of the heart muscle between beats, is indicated by the needle on the dial when the last sound of the disappearing pulse is heard, i.e., when the rush of blood becomes inaudible. Upon further deflation of the cuff, the needle would normally return from its previous measurement position to its starting position. The normal systolic reading of an adult varies from 110 to 130 or 140 mm Hg. Normal diastolic readings vary from 60 to 90 mm Hg.
It is often difficult for an individual taking his own blood pressure or, for that matter, taking another's pressure, to accurately read and note the systolic and diastolic blood pressures during the blood pressure measurement due to the fact that the individual must simultaneously regulate the air bleeder valve, carefully observe the pressure needle as it quickly moves over the dial, and listen to the sounds of the pulses through the stethoscope. Moreover, even skilled personnel, who are trained in the art of taking blood pressure measurements, must either make a mental or very rapid written note of the systolic pressure reading at the appropriate time before the time approaches when the diastolic pressure must be read.
In order to eliminate the drawbacks involved in reliance upon a faulty memory and/or in making very hasty written, and possibly illegible, notes of the systolic and diastolic blood pressure readings, the prior art has proposed automatically-operated sphygmomanometer gauges which have two recording needles in addition to the main pressure needle. The main pressure needle, according to one proposal, automatically carries the two recording needles over the dial until the user decides to manually lock the respective recording needles in position. The prior art has also proposed a pair of recording needles which are moved automatically in response to pressure and electrical pulses and are locked automatically in their measured positions by a ratchet-pawl-solenoid. Examples of such automatically-operated sphygmomanometer gauges can be had by reference to U.S. Pat. Nos. 3,901,217 and 3,056,401.
Exemplary of additional prior art attempts to solve the problem are the following:
U.S. Pat. No. 2,710,001 which issued on June 7, 1955 to Freyburger teaches an automatically operated diastolic and systolic blood pressure indicating instrument which is designed to improve the sensitivity and accuracy of blood pressure readings, and employs two pressure gauges and an automatically operated switching means which senses the pulsation and blood pressure which occurs as the system pressure is released. This invention utilizes a complex system of relief and solenoid valves to achieve the pressurization of each of the two gauges in order to affect the reading of the systolic and diastolic pressures, respectively.
U.S. Pat. No. 3,929,129 which issued on Dec. 30, 1975 to Archambault is directed to a device for checking blood pressure involving the use of two pressure relief valves which are adapted to relieve pressure in an inflatable cuff at two different predetermined pressures, along with the necessary equipment for isolating the first pressure relief valve in order to allow the activation of the second pressure relief valve. The purpose of this system being to allow one to determine when he has either a moderate or a severe case of high blood pressure. The system taught does not allow one to precisely determine the systolic and diastolic pressure readings.
U.S. Pat. No. 4,007,734 which issued on Feb. 15, 1977 to Peters is directed to a blood pressure indicator adapted for self-examination which utilizes a pair of pressure sensing switches on the bladder of the inflatable cuff, which switches are set to either audibly or visually indicate when the maximum systolic or diastolic pressure permissible has been exceeded. Once again, this device does not allow one to accurately determine the pressure readings involved.
U.S. Pat. No. 4,010,739 which issued on Mar. 8, 1977 to Leach teaches a sphygmomanometer construction which incorporates into the pressure indicating gauge additional means for determining when the systolic and diastolic pressures have been reached without the necessity of utilizing a stethoscope or other electronic medium. This device while enabling one to easily determine the precise reading of the blood pressure of the subject, it involves the utilization of much more sophisticated and expensive equipment than that which is called for in the present invention.
U.S. Pat. No. 4,222,390 which issued on Sept. 16, 1980 to Berliner et al. is directed to a sphygmomanometer gauge with multiple indicators to allow one to manually fix the location on the gauge of the systolic and diastolic pressure readings which can then be recorded at a later time. While this is an improvement over the more complex embodiments taught by the prior art, it nevertheless requires the utilization of a more sophisticated and involved gauge construction which is not needed in the present invention.
The sphygmomanometer construction of the present invention allows one taking either their own or another's blood pressure to obtain a more accurate reading of the systolic and diastolic pressure readings by allowing the user to effectively isolate the individual pressure readings for a period of time, thereby enabling him to observe the reading on the pressure gauge which has been frozen at the appropriate moment by the activation of a normally closed, manually operated means which serves to momentarily pressurize and subsequently isolate the pressure gauge.
In the construction of the present invention, the pressure gauge is normally closed off from the ambient pressure in the inflated cuff and only senses the pressure upon the opening and subsequent closing of the manually operated means provided for, which distinguishes this invention over the prior art.
One employing the construction of the present invention would normally pressurize the cuff using the inflatable bulb provided, while checking the heartbeat in the normal fashion. In inflating the inflatable cuff no heartbeat would be detected until the cuff had exceeded the diastolic pressure and subsequently the detected heartbeat would disappear when the pressure in the cuff had exceeded the systolic pressure, at which time the user would be apprised to cease inflating and commence the depressurization sequence.
Upon again initially detecting the heartbeat, the user would manually operate the opening and closing means provided to momentarily expose the pressure gauge to the pressure reading in the cuff.
Such pressure reading would remain on the gauge, due to the fact that the gauge would, by operation of the opening and closing means, subsequently be isolated from the ambient pressure in the cuff, thereby fixing the pressure on the gauge until such time as the means was again manually operated when the user reaches the point of the diastolic pressure reading.
It will, therefore, be apparent that the pressure gauge in the sphygmomanometer construction of the present invention is not utilized in the normal sense as a continuous pressure detecting device but rather as a recording device which will only be affected when the normally closed, manually operated means is opened to allow the gauge to sense the ambient pressure in the inflated cuff.
It is, therefore, an object of the present invention to provide a sphygmomanometer construction which allows the user to easily and accurately determine his or her own or another's blood pressure readings without necessitating the utilization of complicated and expensive automatic equipment and/or other sophisticated devices, such as is required by the prior art.
It is also an object of the present invention to provide for a sphygmomanometer construction which is easily and cheaply assembled from standard components so as to diminish the cost of such devices to the user.
It is a further object of the present invention to provide for a sphygmomanometer construction which allows one to accurately determine systolic and diastolic pressure readings without the degree of uncertainty normally associated with the reading of a pressure gauge while simultaneously manipulating the various other components of a typical blood pressure apparatus.
It is yet another object of the present invention to provide for a simple device which can readily be incorporated into existing sphygmomanometers to permit the modification of existing constructions in order to allow them to operate in the manner provided for.
These and other objects of the present invention will become apparent from the following detailed description of an embodiment of the invention.